Relapse of subacute bacterial endocarditis following penicillin therapy has been observed in some patients with all dosage regimens thus far adopted for general use. A significant reduction in the frequency of relapse has been accomplished in recent years by employing larger doses of penicillin and by extending the duration of treatment to six or more weeks. The refractory cases now encountered are frequently those in which the infection is caused by organisms highly resistant to penicillin, notably enterococci. In other cases, in which the organisms are quite sensitive to penicillin in vitro, relapse following the administration of penicillin is not readily attributable to a property of the infecting bacterial population but is generally ascribed to the nature of the lesion or to a deficiency in the resistance mechanisms of the particular host.
Recent observations on the combined action of penicillin and streptomycin on Enterococcus in vitro, together with the favorable
ROBBINS WC, TOMPSETT R. CHRONIC RECURRENT NONHEMOLYTIC STREPTOCOCCIC ENDOCARDITISReport of a Patient Treated Concurrently with Penicillin and Dihydrostreptomycin. Arch Intern Med (Chic). 1950;86(4):578–584. doi:10.1001/archinte.1950.00230160090008